India, which has over 142 million Facebook users, also holds top rank among 127 countries in terms of researchers contributing to its bug bounty programme, it said in a blog.

"India is home to the largest population of security researchers (205) participating in the Facebook bug bounty programme since its inception in 2011. The country also holds the top spot for most bounties paid (Rs 48.4 million)," Adam Ruddermann, a technical program manager on the Facebook Bug Bounty team, wrote.

A bug is an error or defect in software or hardware that causes a programme to malfunction. It often occurs due to conflicts in software when applications try to run in tandem.

While bugs can cause software to crash or produce unexpected results, certain defects can be used to gain unauthorised access to systems.

Since its launch in 2011, Facebook's bug bounty programme has received over 2,400 valid submissions and has awarded more than USD 4.3 million to 800-plus researchers globally.Under the programme, researchers get rewarded for reporting security bugs, identifying vulnerabilities in Facebook's services or infrastructure that can create security or privacy risks.

In 2015, Facebook's team classified 102 bug bounty submissions as high impact, an increase of 38 per cent over the previous year.

It received 13,233 total submissions from 5,543 researchers in 127 countries and paid USD 936,000 to 210 researchers, who submitted a total of 526 valid reports. The average payout was USD 1,780. India, Egypt, and Trinidad and Tobago received the highest number of payouts.

"Facebook receives more and more high-impact bugs (related reports) from India each year, reflecting the growing sophistication and technical capabilities of the country's engineering schools and cyber security programmes," he said.